When the revolution comes to bury the old ways, it doesn’t leave behind an heir but a pregnant widow, says Martin Amis (alluding to Alexander Herzen) in a novel about the unintended consequences of the sexual revolution. The Women’s Movement turned out to function almost exactly as if designed by horny young men.

The ideal candidate to consider the matter may be Amis — a feminist (indeed, he calls himself a “gynocrat — chicks rule”) who is frequently accused of being a misogynist by the irony starved.

Amis’ sparkling and pointed new novel, “The Pregnant Widow,” which he has called “blindingly autobiographical,” is about a 20-year-old student named Keith spending the summer of 1970 in a castle in Italy that is enchanted by sex. Keith’s girlfriend Lily is sweet yet unexciting. (In her dreams, she washes her hair. She goes shopping).

The object of Keith’s fantasy lust is a friend who lives in another room at the castle, the watermelon-breasted, skyscraper-tall blonde so beautifully endowed with mythic power that her name is actually Scheherazade. As Keith schemes to find a way to be alone with her, a third prospect throws off all calculations: the aggressively unbeautiful Gloria Beautyman, who seems unnervingly advanced in her understanding of everything Keith is up to.

Amis is the supreme swordsman of the English language, but he is no longer primarily interested in being funny. His prose in this sex comedy is angular and tart but dispenses with the gymnastic capering of his best-loved comic novels, such as his masterpiece of ’80s vulgarity “Money” (soon to be a BBC movie).

Characters talk like real people, albeit impossibly clever ones. (Or maybe their verbal cha-cha’ing isn’t impossible: The conversations between Keith and his brother are based on those between Amis and his longtime best mate Christopher Hitchens. Their talks seem likely to occur at grandmaster level.)

What does Amis conclude? There’s a mix of lingering wonder and light regret about the selfishness of it all (“They could all be pretty sure that the 1970s was going to be a me decade. This was because all decades were now me decades.”) but what finally intrigues him most is how the free-sex tsunami crashed into a forgotten island called radical Islam.

That faith turns out to be a significant plot point.

Within the large moral — beware of unforeseen outcomes — there isn’t really another lesson, just canny observation. The way the women of the West unshackled sex from marriage and abandoned modesty as a fashion ideal may have enraged the Islamists — mainly because they realized they were feeling left out of the fun — but there is no going back now.

Yet the last gasp of the sexual revolution will be the laughter of Jihad Inc. Western feminists drastically cut back on the number of children they can bear to bear — but Europe’s Muslim families have no such reservations about fecundity. If one culture features unlimited nooky but the other celebrates unlimited baby-making, which one will win?